Early Hardness of Self-Adhesive Resin Cements Cured under Indirect Resin Composite Restorations ISABEL GIRÁLDEZ, DDS* LAURA CEBALLOS, DDS, PhD § MIGUEL A. GARRIDO, PhD † JESÚS RODRÍGUEZ, PhD ‡ ABSTRACT Purpose: To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations. Materials and Methods: Seven commercial dual-curing resin cements were tested: two were total-etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self-etch (Multilink Automix [Ivoclar Vivadent]), and four were self-adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp., Orange, CA, USA], SmartCem2 [Dentsply, Detrey, GmbH, Konstanz, Germany], and G-Cem [GC CORPORA- TION, Itabashi-Ku, Tokyo, Japan]). Three specimens (0.5 ¥ 6.5mm) of each material were pre- pared for each of three experimental groups: Group 1 (cements allowed to self cure); Group 2 (cements light-cured for 40 seconds); and Group 3 (cements light-cured for 80 seconds). All specimens were cured through a 4-mm-thick composite cylinder (Filtek Z250-A3). Surface microhardness numbers were determined at 20 min after preparation. Results were analyzed by two-way analysis of variance and Student–Newman–Keuls tests (p < 0.05). Results: Superficial hardness was significantly influenced by the resin cement tested (p < 0.0001), the curing mode (p < 0.0001), and their interaction (p < 0.0001). RelyX ARC exhibited the highest mean microhardness values regardless of the curing mode. Light-curing significantly increased the microhardness of all resin cements studied, and these values increased even further with a doubling of irradiation time. Self-adhesive cements exhibited dif- ferent behavior according to the curing mode. RelyX Unicem was highly sensitive to light irra- diation, showing the lowest mean values in the self-curing mode. After light irradiation for 40 or 80 seconds, Maxcem Elite exhibited the lowest mean hardness values of all the resin cements tested. Conclusion: The microhardness of resin cements is highly dependent on the brand. Dual-curing resin cements should always be light irradiated for longer periods than that recommended by manufacturers. *Assistant Professor, Department of Health Sciences III, Rey Juan Carlos University, Avda. de Atenas s/n, 28922 Alcorcón, Madrid, Spain † Assistant Professor, Department of Material Sciences and Engineering, Rey Juan Carlos University, C/ Tulipán s/n, 28933 Móstoles, Madrid, Spain ‡ Full Professor, Department of Material Sciences and Engineering, Rey Juan Carlos University, C/ Tulipán s/n, 28933 Móstoles, Madrid, Spain § Associate Professor, Department of Health Sciences III, Rey Juan Carlos University, Avda. de Atenas s/n, 28922 Alcorcón, Madrid, Spain © 2011, COPYRIGHT THE AUTHORS JOURNAL COMPILATION © 2011, WILEY PERIODICALS, INC. DOI 10.1111/j.1708-8240.2011.00408.x VOLUME 23, NUMBER 2, 2011 116